ควบคุม LED จากแอปโทรศัพท์

Time to put it together: tap a button on your phone and watch an LED turn on. This is BLE control in action. 💡

The phone writes a value to a characteristic, your board reads it, and your sketch switches the LED to match. Simple and powerful.

In setup, declare the LED pin as an output so your board can drive it. This is the same pinMode you already know.

The control characteristic needs PROPERTY_WRITE so the phone is allowed to send commands to it. Read-only would block control.

Attach a callback so your code runs the instant the phone writes. The onWrite method becomes your command handler.

Inside the callback, fetch what the phone sent with getValue. Maybe it is the text 1 for on or 0 for off.

Compare the command, then drive the pin. A 1 turns the LED on, anything else turns it off. That is the whole logic.

It helps to send the new state back so the app stays in sync. A short Serial print also confirms the command really arrived.

No need to build an app yet. A tool like nRF Connect lets you connect and write values to test your control instantly.

In the app, connect to your device, open the writable characteristic, and send 1. The onboard LED should light up right away.

The same write idea powers a full custom app. Once this works, you can control motors, relays, or anything from your phone.

You want the phone to send an on or off command to your board.

A writable characteristic plus a callback turns phone taps into real-world action. You just built remote LED control over BLE. 🎉